In general, semiconductor devices are manufactured by fabrication processes that form electric circuits on a semiconductor substrate, such as a silicon wafer. The fabrication processes usually include various sequences of different process steps, such as deposition, planarizing, photolithography, and ion implantation. Cleaning (such as etching and rinsing) steps are carried out between the various processing steps to remove contaminants from the substrate.
For example, copper is commonly deposited on silicon wafers in semiconductor fabrication. It is well known, however, that copper ions act as a contaminate in semiconductor fabrication. In that regard, copper ions, will diffuse into the silicon and change the conductivity of the silicon. Moreover, copper deposition at the bevel can flake and be unstable and therefore usually requires some etching. Therefore, copper ions are preferably cleaned or etched from all surfaces of the workpiece after a copper deposition process so as to prevent contamination and/or unwanted flaking.
A typical copper cleaning solution for semiconductors is dilute sulfuric peroxide chemistry. This chemistry, or other cleaning solutions, may be used to clean the back side of the workpiece, around the edge (bevel), and on other specific areas on the front side.
In previously designed chambers, masked areas on the wafer prevented the wafer from being fully exposed to the cleaning chemistry, which resulted in contamination. In addition, chemistry collection areas in the chamber for collecting spent cleaning chemistry were not optimized to prevent chemical splash, also resulting in contamination undesirable etching, for example, etching of the front or back side surfaces during the bevel etch process. Moreover, chemistry collection was not optimized for recovery and reuse.
Therefore, there exists a need for a chamber designed to clean a workpiece with reduced masking and improved chemistry collection techniques to minimize splashing and optimize recovery.